Pressure controlled injection valve



May 31, 1949.

J. J. BROEZE PRESSURE CONTROLLED INJECTION VALVE Fig.

Filed June 30, 1947 lnvzn'l'or:

Johannzs J. Broezz His A++orneg Patented May 31, 1949 2,471,605. Irmsssons CONTROLLED mmcrron VALVE Johannes J. Broeze, Delft,Netherlands, assignor to Shell Development Company, San Francisco,Calif., a corporation of Delaware Application June 30, 1947, Serial No.758,107 In the Netherlands January 3, 1947 7 Claims. (Cl. 137-153) Thisinvention relates to atomizers for the injection of fuel into thecombustion spaces of internal combustion-fengines by means of a fuelinjection valve lifted by the fuel pressure such valves being oftenknown as needles or needle valves. More particularly, the inventionrelates to fuel injection nozzles wherein the fuel injection needle issubjected to a liquid, which, when under pressure, urges the needle toits closed position, i. e., for moving it toward or maintaining it onits seat. Such devices are used for injecting combustion fuel eitherdirectly into the engine cylinder or into an auxiliarycombustionatomizer chamber connected with the engine cylinder.

With high-speed engines having injection nozales the needle valves ofwhich are lifted by the fuel pressure it is often difficult to achievesatisfactory control of the dynamic operation of the injection system,comprising the fuel pump, the connecting fuel line and injector nozzle.As a I result, the regularity of the fuel injection is often seriouslydisturbed, particularly when the engines are running at high speed.

It is an object of the present invention to minimize or Obviatethisdisturbance and to provide an improved valve arrangement for achievingsatisfactory control of the operation of the fuel injection system.

A further object is to provide an improved in- Jector nozzle having aneedle valve which is loaded with a liquid confined in a space so as toretard the opening of the needle valve while permitting the rapidclosing thereof.

The invention is based upon the discovery that the aforesaid disturbanceis chiefly due to the sudden increase in the volume within the fuelsystem caused by the lifting of the needle valve. Needle valves whichare lifted by the pressure of the fuel inherently increase the spaceoccupied by the fuel acting on the valve. When an engine is operating ata high speed this sudden increase in the volume of the space causes asharp local reduction of the pressure, and, interferes with the pressurewave occurring between the fuel pump and the fuel injection needle; thisinterference is largely responsible for the disturbance referred to.

In order to avoid the occurrence of this disturbance as far as possible,an atomizer arranged to minimize the sudden increase in the availablefuel space is provided according to this invention, wherein the needlevalve is subjected to the pressure of a loading liquid acting on atleast a portion of the needle and urging the needle to 2 its closedposition. This loading liquid is confined within a closed loading spaceor chamber which has two flow channels: A comparatively wide flowchannel through which loading liquid can only flow into the closedloading chamber; and a comparatively narrow flow channel permitting flowinto or out of said loading chamber, or, if desired, only out of saidloading chamber. .These channels communicate with a reservoir containinga supply of the loading liquid, which might be maintained underpressure. If desired, the narrow flow channel need not be connected tothe. reservoir but may have its mouth disposed for discharge to the openor into any other receptacle.

The loading liquid need not be under pressure at all times; thus, whenthe invention is applied to injectors having spring loaded needlevalves,

or spring loading for the needle valve .inay be omitted entirely, thefunction usually performed by the spring being partially or whollyperformed by the loading liquid. In this case it is, according to thisinvention, preferable to connect both the wide channel and the narrowchannel from the loading chamber to the source of liquid pressure, forexample, to the aforesaid reservoir. A suitable pressure is thenmaintained on the loading liquid, as by connecting a pressure regulatedfeed pump and/or a standpipe to the reservoir. It is preferable in sucha case to connect the loading chamber and reservoir by a bore fittedwith a back pressure valve with a narrow perforation in it, the latterforming the narrow flow channel.

The invention will be further illustrated with reference to the drawingsforming a part of this specification, wherein:

Fig. l is an axial section of an injector embodying the presentinvention;

Fig. 2 is an enlarged detail view of the valve for controlling the flowof loading liquid; and

Fig. 3 is a cross-sectional view taken on line 3-,3 of Fig. 2. p

The injector comprises a casing l which may, if desired, be formed ofseveral parts; its lower portion 2 is adapted to fit into a well in theengine block leading into the combustion spacev of the cylinder, i. e.,either directly into the cylinder or into a connectingatomizing-combustion chamber. The casing has a passage 3 incommunication with a hollow or chamber 4 for the supply of fuel whichmay be fed to the casing by a suitable fuel line attached to a fitting5. The end of the passage 3 is closed with a plug 0. Fuel from thechamber 4 is discharged into the combustion space via the atomizerducts 1. these ducts being normally closed by means of a needle valve 8,slidably mounted in a central bore in the casing and having a close fittherewith. The end a of-the needle rests on the portion of the llowerwall of the chamber immediately surrounding the central fuel dischargepassage to the atomizer ducts I, said portion forming a valve seat. Thisend of the needle is of reduced crosssection, whereby the annular faceat the end of the larger portion is exposed to the pressure of the fueland the needle may be lifted in response to a rise in the pressure ofthe fuel in the chamber 4. As is understood in the art, the fuelissupplied from a suitable fuel pump which increases the fuel pressureperiodically in synchronism with the engine and is actuated, forexample, by a cam device. The pressure rise causes the lifting of theneedle and the injection of the fuel into the combination space at thedesired instant.

The central bore of the casing is enlarged at a providing a closedhollow space or chamber above the needle which is filled with a loadingliquid, such as oil. This chamber is herein referred to as the loadingchamber. A further enlarged chamber ill at the top of the casing is alsofiliedwith loading liquid and is in communication with a source ofpressure through a passage H in the top closure l2. This space it formsthe reservoir for the loading liquid. The chambers I and ii areinterconnected by a bore l3.

Flow of loading liquid through the bore I 3 is regulated by means of aback pressure valve ll provided with radial fins 'II in slidingengagement with the walls of the bore II. It carries a trunco-conicalvalve head I. adapted to seat upwardly against the lower mouth of thebore i3. being urged upwardly by a spring II. This spring rests on thetop of the needle 0 and tends to urge the needle to its seat. The springI 1 is, 50,

however, in the preferred form of the invention of comparatively lightconstruction, so as to play a minor'part in urging the needle to itsclosing position, the needle being urged toward its seat mainly by theloading liquid; the spring I! may, if desired, not bear against theneedle valve, but rest on a shoulder on the casing I or even be omittedentirely, the needle being then closed entirely by the force of theloading liquid. The valve H in this case rises to its closed position byfluid pressure immediately after the needle valve 0 has started itsupward movement. The valve is provided with a bore I which isconstricted near the top to form a narrow channel l0.

It will be seen that the chambers 0 and III are interconnected by twochannels: The open portion of the bore l3 between the fins l5 forms thewide channel, through which loading liquid can flow freely downwardlyinto the loading chamber 0 around the valve it between the fins when thehead I0 is off its seat; the narrow channel is formed by the bore II andconstricted channel l0. Since the spring I! is light, the valve willdescend whenever the pressure in the chamber 0 falls below that in thechamber ll, 75 greater or lesser number of parts without departpermitting a rapid downward flow of loading liquid. When the pressure inthe chamber 0 is equal to or exceeds that in the chamber l0, however,the spring I! closes the valve and the upward flow of liquid isprevented. Liquid can then flow upwardly only at a slower rate throughthe narrow channel l9.

The injector operates as follows: The loading liquid in the chamber IIIis maintained at a pres-' sure :1. As long as the needle valve is in itsclosed position, the loading chamber 0 is at the same pressure. When thefuel pressure in the passage 3 exceeds a certain value; whichwlll dependupon various characteristics of the injector, such as the size ofneedle, the stiffness of the spring I] and the pressure p, the valve 8is lifted.

As soon as the needle valve is lifted the pressure in loading chamber 9(and. therefore, also the loading on the upper end of the needle)increases sharply, because the loading liquid contained in this chambercan escape only to chamber l0 through the narrow channel is. Thischannel is so narrow that a considerable resistance against the upwardmovement of the needle is created.

As a result, the needle valve 8 islifted very gradually, so that thevolume of the chamber 4 is increased only gradually and the occurrenceof the previously mentioned disturbin interference with the pressurewave in the fuel supply system is entirely or for the greater partobviated.

For closing the needle the full pressure p is available, because theloading liquid can flow from chamber ID to loading chamber 9 withouthaving to' overcome any appreciable resistance. Hence, the needle 8 canclose rapidly.

In a practical embodiment the needle diameter above the narrower portion8a was 4 mm., the lift of the needle 0.2 mm. and the pressure p 200atmospheres. The quantity of loading liquid which must pass from chamber9 to chamber i0 through the narrow channel I! when the needle rises willthen be about 2.5 cubic mm. If the speed of the engine is 2000 R. P. M.and the opening is to be effected in 6 degrees of travel of the crank,i. e., in 0.5 l0- seconds, the displacement velocity will be 5,000 cubicmm. per second.

If the narrow channel I! is given a diameter of about 0.26 mm., and oilis used as the loading liquid, an increase in pressure of about 50atmospheres is obtained, which constitutes a considerable resistanceagainst too rapid opening of the needle; this resistance is attained inaccordance with the present invention with constructionally controllablemeans.

The invention can also be applied to injectors wherein the needle isbrought to the closed portion or maintained there by means of springpressure; in this case the loading liquid in the chamber [0 need not bemaintained under pressure. However, application of liquid pressureofiers the advantage that the moving parts of the injector can bedesigned lighter and the needle cannot be subjected to lateral loading,so that it moves freely within its guides. The pressure p can beobtained by taking some oil from the fuel injection system; the pressurep can be very easily regulated, for example, as a function of the numberof revolutions per minute of the engine.

Instead of forming the narrow channel as a bore in the back pressurevalve ll, a leakage opening may be provided in the valve head I6 .or inthe mouth of the bore II which forms the valve seat.

The injector may, of course, be constructed of a 2,471,coc

ing from the spirit and scope of the invention. Thus, the loading space9 may be formed in a housing or part which is separate from the cas ingl.

I claim as my invention:

1. A pressure controlled injection valve, for internal combustionengines comprising a casing having an axially extending guide bore, afuel inlet passage, a fuel chamber at one end of the bore, a fueldischarge passage in said casing leading from said fuel chamber andprovided with a valve seat, a loading chamber for loading liquidseparate from saidfuel chamber and in communication with said bore, anda reservoir for loading liquid; a valve member having a piston portionwithin said guide bore coacting with said valve seat for controllingsaid discharge passage and having a surface facing toward said seatexposed to the fuel pressure in said fuel chamber and a surface facingin the opposite direction exposed to the pressure of the loading liquidin the loading chamber, whereby fuel pressure will tend to open saidvalve member and loading liquid within said loading chamber will opposethe opening thereof; a narrow fiow channel formed in said casing for theloading chamber adapted to permit the restricted flow of loading liquidout of the loading chamber; and a wider flow channel having a valveadapted to permit the substantially free flow of loading liquid from thereservoir into the loading chamber and prevent the free flow of loadingliquid out of the loading chamber.

2. An injection valve as defined in claim 1 wherein the narrow flowchannel interconnects the loading chamber and the reservoir.

3. An injection valve as defined in claim 1 wherein the valve in thewider flow channel is a back pressure valve adapted to permit the flowof loading liquid from the reservoir into the loading chamber when thepressure therein is lessv 40 than the pressure in the reservoir.

4. An injection valve as defined in claim 3 wherein the back pressurevalve is provided with I narrow perforations forming said narrowfiowchannel.

5. A pressure controlled injection valve for internal'combustion enginescomprising a casing having an axially extending guide bore, a fuel inletpassage, a fuel chamber at one end of the bore, a fuel discharge passagein said casing leading from said fuel chamber and provided with a valveseat in axial alignment withsaid bore space, a loading chamber forloading liquid in said chamber at a point removed from said fuel chamberand in communication with said bore, a reservoir for loading liquid alsoin said casing and a bore connecting said loading chamber and reservoir;a valve member having a piston portion within said guide bore coactingwith said valve seat for controlling said discharge passage and having asurface facing toward said seat exposed to the fuel pressure in saidfuel chamber and a surface facing in the opposite direction exposed tothe pressure of the loading liquid in the loading zchamber; whereby fuelpressure will tend to open said valve member and loading liquid withinsaid loading chamber will oppose the opening thereof; a back pressurevalve controlling the flow of loading liquid between the loading chamberand the reservoir adapted to permit the substantially unobstructed flowof loading liquid from the reservoir into the loading chamber; and anarrow flow channel connecting said loading chamber and reservoir andadapted to permit the restricted fiow of loading liquid from the loadingchamber'into the reservoir.

6. An injection valve as defined in claim 5 comprising a spring withinsaid loading chamber arranged to urge the back pressure valve and thevalve member to their closed positions.

7. An injection valve as defined in claim 5 wherein the narrow flowchannel is a perforation in the back pressure valve.

JOHANNES J. BROEZE.

REFERENCES CITED UNITED STATES PATENTS Name Date Miller -a-.. May 13,1947 Number

